fix(commands)+docs: even out :NuwikiUISelect; exhaustive subgroup key lists

- ftplugin/vimwiki.vim: add buffer-local :NuwikiUISelect to the Vim path
  (it previously existed only on the Neovim path, contradicting the docs'
  "buffer-local on every .wiki buffer" claim — a global fallback masked it).
  Now symmetric with :VimwikiUISelect.

- Make every keymap subgroup description list all of its bindings instead
  of trailing with "…": the README mappings-subgroups table, the README
  config-example comments, the README g:nuwiki_no_<group>_mappings rows,
  the doc/nuwiki.txt group→keys list, and the lua/nuwiki/config.lua comment.
  Also fixes the doc list that had dropped aH/iH from text_objects and adds
  the mouse group. Each notes that the <Leader>w prefix follows map_prefix.

helptags validates (no dup tags); all keymap suites pass (266+18+21 Vim,
275 Lua); :NuwikiUISelect confirmed defined on a Vim .wiki buffer.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lua/nuwiki/config.lua

@@ -42,17 +42,18 @@ M.defaults = {
   -- Per-buffer glue. Each subgroup mirrors vimwiki's
   -- `g:vimwiki_key_mappings` shape and can be flipped off
   -- independently to suppress that group of keymaps.
+  -- The <Leader>w prefix in wiki_prefix/links/html_export follows map_prefix.
   mappings = {
     enabled       = true,
-    wiki_prefix   = true,  -- <Leader>w*
-    links         = true,  -- <CR>, <S-CR>, <Tab>, <BS>, +, …
-    lists         = true,  -- <C-Space>, gln/glp/glx, gl<Space>, o/O, …
+    wiki_prefix   = true,  -- <Leader>w{w,t,s,i}, <Leader>w<Leader>{w,y,t,m,i}
+    links         = true,  -- <CR>, <S-CR>, <C-CR>, <C-S-CR>, <D-CR>, <M-CR>, <BS>, <Tab>, <S-Tab>, + (n/x), <Leader>w{n,d,r}, <Leader>wc (n/x)
+    lists         = true,  -- <C-Space>, gnt, gln, glp, glx, glh, gll, gLh, gLl, glr, gLr, gl{-,*,#,1,i,I,a,A}, gL{…}, gl, gL, o, O; insert <C-D>, <C-T>, <C-L><C-J/K/M>, <CR>
     headers       = true,  -- =, -, ]], [[, ]=, [=, ]u, [u
-    table_editing = true,  -- gqq, gq1, gww, gw1, <A-Left>, <A-Right>
+    table_editing = true,  -- gqq, gq1, gww, gw1, <A-Left>, <A-Right>; insert <Tab>, <S-Tab>
     diary         = true,  -- <C-Down>, <C-Up>
-    html_export   = true,  -- <Leader>wh, <Leader>whh
+    html_export   = true,  -- <Leader>wh, <Leader>whh, <Leader>wha
     text_objects  = true,  -- ah, ih, aH, iH, al, il, a\, i\, ac, ic
-    mouse         = false, -- <2-LeftMouse>, <RightMouse>, …  (opt-in)
+    mouse         = false, -- <2-LeftMouse>, <S-2-LeftMouse>, <C-2-LeftMouse>, <MiddleMouse>, <RightMouse> (opt-in)
   },
 
   -- Folding. `'lsp'` uses the server's `foldingRange`